(LifeScript Health News) Male circumcision can reduce men’s risk of contracting human papillomavirus (HPV) and herpes, according to a new study published in the New England Journal of Medicine. Circumcision has already been shown to prevent heterosexual transmission of HIV infection in men.

Researchers from Makerere University in Uganda and Johns Hopkins University tracked more than 3,300 Ugandan men for two years. The study showed that adult male circumcision reduced the risk of contracting herpes by 25%; the risk of HPV decreased by 35%. The cause is uncertain, but researchers believe that when the foreskin retracts during sex, the penis is exposed to infection. The foreskin can also provide a moist area for viruses to thrive.

According to the Centers of Disease Control and Prevention, more than 45 million Americans age 12 and older have herpes simplex Type 1, the type that causes genital lesions. About 20 million Americans are infected with HPV, which causes cervical cancer in women.